Seat back inertia latch and sector system

Abstract

A motor vehicle seat recliner (10) includes upper and lower attachment members (12 and 14) joined at a hinge point (16). An adjuster (58) operates to establish a substantially fixed angular position between the members. An inertia latch (60) operative to disengage the adjuster from the upper attachment member as a function of recliner attitude and acceleration includes elements (52 and 62) defining cooperating engagement surfaces (98 and 99) which are relatively displaceable upon incipient movement of one of the members in a predetermined direction from a pre-latched position to a release position when the movement is relatively slow and to an engaged position when the movement is relatively fast.

I claim: 
     
       1. A motor vehicle seat recliner comprising: a lower recliner structure for supporting a seat cushion;   an upper recliner structure for supporting a seat back, said upper and lower structures joined at a hinge point;   a sector member mounted to said lower recliner structure for limited rotation about an axis of said hinge point and defining a first abutment surface;   adjuster means carried by said lower recliner structure and engaging said upper recliner structure for selective, substantially fixed angular positioning of said sector member to establish an upper recliner stop position;   a latch member carried by said upper recliner structure for limited relative rotation about a second pivot axis offset from and generally parallel to said hinge point axis, said latch member defining a second abutment surface engageable with said first abutment surface to prevent forward rotation of said upper recliner structure as a function of recliner acceleration and attitude, said first and second abutment surfaces being in at least partial overlapping engagement during nominal rest conditions and relatively displaceable upon incipient movement of said sector member in a predetermined direction from a closely spaced pre-latched position to a widely spaced release position when said movement is at a relatively slow rate; and   said sector member and said latch member including portions which are in sliding contact during incipient movement of said latch member from said prelatched position to an abutting engaged position with said sector member when said movement is at a relatively high rate.   
     
     
       2. The seat recliner of claim 1, further comprising manual release means operable to displace said latch member to said release position independently of recliner attitude and acceleration. 
     
     
       3. The seat recliner of claim 1, wherein said latch member has a characteristic center of gravity offset from said second pivot axis. 
     
     
       4. The seat recliner of claim 1, wherein said latch member defines a tapered abutment surface engageable by a manual release actuator operable to displace said latch member to said release position independently of recliner attitude and acceleration. 
     
     
       5. The seat recliner of claim 1, wherein said sector member defines an arcuate toothed portion and said adjuster mechanism comprises an operator controlled electric motor drivingly engaging said toothed portion through a drivetrain. 
     
     
       6. The seat recliner of claim 1, wherein one of said portions which is in sliding contact defines a radially outwardly extending axial ridge operative to establish at least momentary line contact with said other surface portion during resetting movement of one of said members. 
     
     
       7. The seat recliner of claim 6 wherein portions which are in sliding contact have a predetermined characteristic coefficient of friction operative to effect continued sliding engagement as said latch member rotates from said pre-latch position to said release position, and is operative to effect sliding engagement as said latch member rotates from said pre-latch position to said engaged position. 
     
     
       8. The seat recliner of claim 1, wherein the latch member comprises: a hook portion and a spaced counterweight portion, the second abutment surface formed on said hook portion, the portion of said latch member disposed in sliding contact with said sector member formed between said hook portion and said counterweight portion.   
     
     
       9. The seat recliner of claim 8, wherein the characteristic center of gravity of said latch member is offset from said second pivot axis of said latch member. 
     
     
       10. The seat recliner of claim 8, wherein said hook portion is closely spaced and non-engaged with said first abutment surface in a pre-latched position of said latch member. 
     
     
       11. A motor vehicle seat recliner comprising: a lower recliner structure for supporting a seat cushion;   an upper recliner structure for supporting a seat back, said upper and lower structures joined at a hinge point;   a sector member mounted to said lower recliner structure for limited rotation about an axis of said hinge point and defining a first abutment surface;   adjuster means carried by said lower recliner structure and engaging said upper recliner structure for selective, substantially fixed angular positioning of said sector member to establish an upper recliner stop position;   a latch member carried by said upper recliner structure for limited relative rotation about a second pivot axis offset from and generally parallel to said hinge point axis, said latch member having a hook portion and a spaced counterweight portion, the characteristic center of gravity of said latch member being radially offset from said second pivot axis of said latch member, a second abutment surface formed on said hook portion engageable with said first abutment surface to prevent forward rotation of said upper recliner structure as a function of recliner acceleration and attitude, said first and second abutment surfaces being in at least partial overlapping engagement during nominal rest conditions and relatively displaceable upon incipient movement of said sector member in a predetermined direction from closely spaced pre-latched position to a widely spaced release position when said movement is at a relatively slow rate; and   said sector member and said latch member including engagement surface portions which are in sliding contact during incipient movement of said latch member from a pre-latched portion to an abutting engaged position with said sector member when said movement is at a relatively high rate wherein said engagement surface portions have a predetermined characteristic coefficient of friction operative to effect rolling engagement as said latch member rotates from said pre-latch position to said release position, and are operative to effect sliding engagement as said latch member rotates from said pre-latch position to said engaged position, one of said engagement surface portions defining a radially outwardly extending axial ridge operative to establish at least momentary line contact with said other engagement surface portion during resetting movement of said latch member.